Adaptable strainer for paint guns



Dec. 28, 1965 w. o. SCHAUB 3,225,931

ADAPTABLE STRAINER FOR PAINT GUNS Filed May 51. 1961 INVENTOR.

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United States Patent 3,225,931 ADAPTABLE STRAINER FOR PAINT GUNS Willy O. Schaub, 1507 Maple Ave., Evanston, Ill. Filed May 31, 1961, Ser. No. 113,934 2 Claims. (Cl. 210251) In paint guns it is important to strain the paint just as it is drawn into the intake tube. According to my prior invention, Patent No. 2,732,946, a very easily used and inexpensively produced strainer was provided. This was in the form of a small piece of metallic mesh screening rolled to form a cone, the tip of the cone being closed as by a touch of solder, and the 'base of the cone being curled to form a rim. This could be inserted tip first into an intake tube of the proper size and it would frictionally hold itself in place peripherally sealed sufficiently to the tip of the tube so that all the paint flowing into the tube would flow through the body of the cone. It could easily be removed by gripping the curled rim which remained outside of the tube and slipping it out. It was so easily cleaned that it could be used over and over for different colors of paint. In the event it should eventually wear out it was easily replaced.

Paint guns do not all have their intake tubes of the same diameter. Accordingly, it has been necessary in the past to provide three sizes of strainers of the type mentioned for the common sizes of intake tubes.

According to the present invention, one size of strainer is sufficient. A strainer having the desired degree of adaptability for the three common sizes is provided by forming the strainer with its conical body substantially the same as before, but with the screening material doubling back in the form of a cuff of tubular nature slightly spaced from the body of the cone and having a curled rim at its free end. Again the strainer is inserted into the tube, tip first, but instead of being dependent upon the correct fit between the base of the cone and the tube, it is now able to suitably engage the tube by having the cuff portion of the strainer surround the tube and frictionally engage it. It has been found that a strainer of this construction is quite adaptable to different sizes and is thoroughly satisfactory on the three common sizes of intake tubes. A spring clamp can be provided around the cuff, but it is probably more necessary for the users reassurance then it is for security where the three common sizes are used. 'If an abnormal size is used, it may be necessary for security.

Additional objects and advantages of the invention may be apparent from the following description and from the drawings.

Designation of figures FIGURE 1 is a side elevational view, partially fragmentary, more or less diagrammatically indicating a paint gun with an intake tube extending to the bottom of its bowl.

FIGURE 2 is an enlarged fragmentary view of the end of the intake tube with the strainer of the present invention applied thereto.

FIGURE 3 is an end view of the structure shown in FIG. 2.

General description Although the following disclosure offered for public dissemination is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.

3,225,931 Patented Dec. 28, 1965 'ice Although the paint gun may be of any form, it is diagrammatically represented as having a housing 11 carried by a handle 12 and equipped with a paint supply bowl 13. An intake tube 14 extends down approximately to the bottom of the bowl 13. When the paint gun mechanism, :sufiiciently represented in this case by a solenoid 16, is suitably actuated, paint is drawn into the bottom end of intake tube 14 and is sprayed from a suitable nozzle 17.

It is important that the paint drawn into intake tube 14 be completely free from lumps or particles which might clog the nozzle 17, and for this reason it has been common to provide a strainer for the intake tube 14. The strainer of this invention is seen in FIG. 1 at 18.

Strainer details The nature of the present invention is probably best seen from FIG. 2. Here the intake tube 14 and the strainer 18 are shown in cross section. The conical body 21 has been inserted first into the end of the intake tube 14. The tip 22 of the body is sealed with a touch of solder, most conveniently being accomplished by dipping the tip into molten solder. A cuff 23 surrounds the end portion of tube 14. The cuff 23 is a continuation of the same material which forms the body 21, the cuff 23 and body 21 being connected by a re-entrant curved portion 24. In other words, the material extends from the base of the body portion outwardly all around the body and then doubles back along but spaced from the body portion.

The original shape of the strainer before application to the intake tube 14 may have been substantially as shown, but is more likely to have been substantially different. For example, the conical con-tour of the body 21 may have extended all the way to the re-entrant curve portion 24, which would then have had a slightly greater overall diameter. In this instanee, the base of the cone would have had a slightly larger outside diameter than the inside diameter of the intake tube 14. Nevertheless it easily accommodates itself to the tube in such a situation. Part of the contraction necessary for this accommodation is elastic and hence the body 21 grips the inside surface of the wall of tube 14 with sufficient resilient friction to dependably hold the strainer in the tube.

Also the spacing between the strainer body 21 and cuff 23 is preferably slightly less than the wall thickness of the common intake tube 14 and the tube is resiliently gripped between the base portion of the body 21 and the cuff 23. Even if the tube 14 is slightly larger so that the cone 21 does not become contracted by insertion, the tube will still be gripped resiliently by the cuff 23, which, in this instance, will be expanded in order to surround the end portion of the tube 14. The illustrated outwardly curled rim 25 will add to the resilient gripping force, and also serves as a cam to aid in stretching the cover as it is applied onto the large size tube.

A spring clamp 26 has been shown surrounding the cuff 23. This provides greater certainty in properly holding the strainer in the position shown in FIG. 2, especially if the strainer should happen to be used with an unusual size of intake tube, one outside the rather wide limits for which the present strainer is designed.

It is to be understood that the same materials used heretofore for the screening may be used according to the present invention. A fine mesh bronze screening is preferred.

'It is apparent that according to the present invention a manufacturer or a supply house need make or carry only a single size of strainer for a rather wide variation in tube sizes of the guns. This represents both an economy and a convenience. It is even a convenience for customers because they often have not known, when seeking a replacement strainer for a gun not carried with them, which of the three sizes with which they were faced was the correct size.

What is claimed is:

1. The combination 'of a paint gun having a bowl for holding a supply of paint and a gun mechanism having an intake tube extending deep in the bowl; and a slip-on strainer including a body of wire mesh screening formed to generally conical shape, continuing beyond the larger end of the body outwardly through a return bend all around the body, and back along but spaced from the body as a generally cylindrical cuff tending to retain its shape and resiliently resist enlargement and curled outward-1y to form a rim at the free end of the cuff; the length of the cuff being several times longer than its spacing from the body adjacent the return bend to provide, over a substantial length, closely spaced walls adapted to cling to a variety of tube diameters, with the cuff resiliently gripping the outside surface of larger tubes and the body partially contracted by smaller tubes to a cylindrical shape parallel to the cuff and resiliently pressing on the inside surface of smaller tubes.

2. A slip-on strainer for paint gun intake tubes and the like shaped of wire mesh screening formed to a shape in which it is firm but from which it can yield with resiliency as applied to different sizes of paint gun tubes, including a body of generally conical shape with a slim conical taper, and with the wire mesh continuing beyond the larger end of the body outwardly through a return bend all around the 'body, and back along but spaced from the body as a generally cylindrical cuff tending to retain its shape and resiliently resist enlargement, and

curled outwardly to form a generally tubular rim at the free end of the cult; the length of the cult being several times longer than its spacing from the body adjacent the return bend to provide, over a substantial length, closely spaced walls adapted to cling to a variety of tube diameters, with the cuff resiliently gripping the outside surface of larger tubes and the body partially contracted by smaller tubes to a cylindrical shape parallel to the cuff and resiliently pressing on the inside surface of smaller tubes.

References Cited by the Examiner 

1. THE COMBINATION OF A PAINT GUN HAVING A BOWL FOR HOLDING A SUPPLY OF PAINT AND A GUN MECHANISM HAVING AN INTAKE TUBE EXTENDING DEEP IN THE BOWL; AND A SLIP-ON STRAINER INCLUDING A BODY OF WIRE MESH SCREENING FORMED TO GENERALLY CONICAL SHAPE, CONTINUING BEYOND THE LARGER END OF THE BODY OUTWARDLY THROUGH A RETURN BEND ALL AROUND THE BODY, AND BACK ALONG BUT SPACED FROM THE BODY AS A GENERALLY CYLINDRICAL CUFF TENDING TO RETAIN ITS SHAPE AND RESILIENTLY RESIST ENLARGEMENT AND CURLED OUTWARDLY TO FORM A RIM AT THE FREE END OF THE CUFF; THE LENGTH OF THE CUFF BEING SEVERAL TIMES LONGER THAN ITS SPACING FROM THE BODY ADJACENT THE RETURN BEND TO PROVIDE, OVER A SUBSTANTIAL LENGTH, CLOSELY SPACED WALLS ADAPTED TO CLING TO A VARIETY OF TUBE DIAMETERS, WITH THE CUFF RESILIENTLY GRIPPING THE OUTSIDE SURFACE OF LARGER TUBES AND THE BODY 